We make tailored and customized trays right here in our office. That way your customized trays can be fitted and picked at right here. The $99 includes the initial trays and 4 whitening vials, then every 6 months when you come for your cleaning and check up you will get a whitening vial for free! You are able to purchase additional vials (if necessary to achieve a lighter shade) separately for $15 each.